It is frequently necessary to dispense particulate matter into batches of known size and there are many machines and systems for so doing.
One type of machine for dispensing quantities of particulate materials consists of a hopper connected to a forwarding mean such as a vibratory conveyer which creates a fairly steady pouring of the particles.
For pouring set quantities of regular particles such as the proverbial carob seeds which are very standard in same and shape, wear resistant and rarely broken, and thus became the standard for weighing precious stones (the Karat), dispensing by weight is a viable option. For less standard items, this is not a satisfactory option.
By way of example, it may be required to sort rough diamonds into packages of approximately equal samples, perhaps to enable different evaluators to estimate the quality and worth of the whole. It will be appreciated that a random sample of diamonds follows a Weibull distribution. Weight is less than satisfactory as a means of batching, and counting is desired. Indeed, even if batched by weight, accurately counting the number of particles in the sample is extremely important.
For items that are brittle and easily broken, such as many medicines that are dispensed in tablet form, broken items make counting unsatisfactory for dosing purposes, particularly since there may be desire to know how many broken tablets are within a sample, and these may even be considered as scrap, so batches are required to have preset amounts of whole tablets. Essentially in such scenarios, the number of broken items (pills, tablets) is irrelevant, provided broken items can be identified during the pouring and discounted from the total. Nevertheless, it may be very important for all batches to contain their compliment of pills, but a few extra can be extremely expensive and wasteful.
U.S. Pat. No. 5,473,703 to Smith titled “Methods and apparatus for controlling the feed rate of a discrete object sorter/counter” describes an object sorter/counter for controlling the feed rate of a sorter/counter that includes a feed bowl which is oscillated by an adjustable amplitude vibrator, and an exit assembly having a chute with a sensor array for registering the passage of objects through the exit assembly.
The feed bowl is provided with a shutter which interposes a photo-detector and a light source so that light from the light source is blocked from detection by the photodetector intermittently as the feed bowl oscillates. A circuit coupled to the photodetector generates a series of pulses having widths inversely proportional the amplitude of bowl oscillation. A controller adjusts the vibrator to oscillate the feed bowl at a predetermined amplitude until the sensor array senses a first object. The controller then adjusts the vibrator to oscillate the feed bowl at a lower amplitude and monitors the sensing of other objects. Time intervals between objects being sensed are monitored and the controller adjusts the vibrator to oscillate the feed bowl at a lower or higher amplitude to maintain a constant feed rate. A count of objects sensed is maintained and compared to a predetermined maximum count. When the count of objects equals a predetermined number less than the maximum count, the controller adjusts the vibrator to oscillate the feed bowl at a lower amplitude to lower the feed rate. When the count of objects equals the maximum count, the controller activates a gate closing the chute.
The above system pours at an ever lower rate as the pouring gets closer to the total. This creates bottlenecks. Each pouring cycle is an individual activity that is time consuming, adding to the cost of production.
U.S. Pat. No. 6,659,304 to Geltser and Gershman, titled “Cassettes for systems which feed, count and dispense discrete objects” describes a high capacity cassette for an object counting and dispensing system, that includes a substantially horizontal base including an exit hole, a peripheral wall about the base and having an internal periphery, the base and the peripheral wall defining a reservoir adapted to store a plurality of the discrete objects, and a structure about the internal periphery which feeds the discrete objects in single file toward said exit hole.
It will be appreciated that feeding discrete objects in single file, i.e. pouring pills one at a time, enables extremely accurate counting. It is, however, not fast, and the throughputs of this and similar systems is not high. This means that efficiencies are low. Indeed, the dispensing is often the bottleneck of manufacturing plants of this type, and thus contributes significantly to the cost of the product.
It will be appreciated that there is a general need for increased accuracy in counting, particularly to minimize other-shooting the desired total, whilst speeding up the counting and dispensing process.
To determine the actual number of objects poured, it is useful to film the falling objects. By monitoring objects interrupting the illumination of a light source onto a pixilated array, it is possible to count objects being poured in real time. Such systems, including both feeder and optical system, are known.
For example, U.S. Pat. No. 5,768,327 to Pinto et al. titled “Method and apparatus for optically counting discrete objects” describes an object counter includes a feeding funnel having a frustroconical section, the narrow end of which is coupled to a substantially vertical feeding channel having a substantially rectangular cross section. A pair of linear optical sensor arrays are arranged along adjacent orthogonal sides of the feeding channel and a corresponding pair of collimated light sources are arranged along the opposite adjacent sides of the feeding channel such that each sensor in each array receives light the corresponding light source. Objects which are placed in the feeding funnel fall into the feeding channel and cast shadows on sensors within the arrays as they pass through the feeding channel. Outputs from each of the two linear optical arrays are processed separately, preferably according to various conservative criteria, and two object counts are thereby obtained. The higher of the two conservative counts is accepted as the accurate count and is displayed on a numeric display. In another embodiment, four sensor arrays and light sources are provided. The third and fourth sensor arrays and corresponding light sources are located downstream of the first and second arrays. The outputs of each of the sensor arrays are processed separately and the highest conservative count is accepted as the accurate count and is displayed on a numeric display.
European Patent Attorney Number EP1083007 titled “Method and apparatus for sorting granular objects with at least two different threshold levels” describes a method and system wherein granular objects flowing in a continuous form are irradiated by light. The resulting image element signals from a solid-state image device are binarized by a threshold value of a predetermined luminance brightness determined for detecting a defective portion of a granular object of a first level, and the above image element signals are also binarized by a threshold value of a predetermined luminance brightness determined for detecting a defective portion of a second level. The second level is for a tone of color heavier than that of the first level. When a defective image element signal is detected from the binarized image elements, an image element of a defective granular object at the center location is specified and the sorting signal is outputted to act on the center location of the defective granular object corresponding to the image element at the specified center location. A granular object having a heavily colored portion which, even small in size, has influence to the product value can be effectively ejected. Sorting yield is improved by not sorting out the granular objects having a defective portion which is small and only lightly colored thus having no influence to the product value.
There is a general need for dosing systems and methods for dosing discrete numbers of objects into batches or samples that are fast and accurate. The present invention addresses this need.